Another side by side HPS VS DE HPS VS COB LED

Discussion in 'LED and other Lighting' started by MeGaKiLlErMaN, Sep 7, 2016.


    MeGaKiLlErMaN Well-Known Member

    I was going to post this in my grow adventures however I feel that the info I have from today is a good start as I understand that not alot of people use light meters. I know its not the end all yet but it is the starting line. We have all heard that COBs can out preform any other light in the efficiency area. While I agree and have seen many results.... I trust no one. So I finally got my (cheap HydroFarm) PAR meter in the mail today (if anyone knows where the calculation adjustments are for the meters let me know) From most of the videos Ive seen there isnt much difference between all of the different meters.. Just search youtube.

    That brings me to the PPFD results (aka the only ones that mater) for the HPS, DE HPS, and COBS.
    All of these tests were in a 5x4 area and the light was 2ft exactly away. I measured every square foot.
    (I plan on doing more in a 4x4 but I have to rebuild the COBS for that.) 2 of the sides had reflection for all tests. (in a corner)
    SO here are the numbers that I got out of this

    2ft distance DE HPS 1000W GROW STATION 4x5
    1ST ROW 250 450 586 414 200
    2ND ROW 270 630 1080 689 249
    3RD ROW 280 648 1100 598 232
    4TH ROW 204 362 408 325 170


    1000W HPS 8in HOOD REFLECTOR 4x5
    1ST ROW 176 357 443 324 158
    2ND ROW 240 554 720 504 264
    3RD ROW 260 645 816 600 270
    4TH ROW 198 270 320 253 140


    BARE COB LED IN A 5x5 800W
    ROW 1 270 425 530 450 430
    ROW 2 390 460 560 445 421
    ROW 3 400 470 584 463 427
    ROW 4 330 435 563 454 424

    329.65 PPFD

    Seems like an open and shut DE HPS win huh? I mean what could make anything change? Except that everything was at 2ft. After seeing what Im getting I can run around 1ft away with the COBS bare. And in the next test Ill be testing everything in a 4x4 at the preferred height.

    Stay tuned if you like, or let me know if you see any errors. This will be a grow between all of the lights as soon as I find a 4th strain. ( my purple guy isnt close to done with his new strain)

    The difference between this thread and my Adventures thread id that this is specifically metric based and the other is more of a results/ what Im dealing with and build log.
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    Malocan Well-Known Member

    i wonder, if 2ft distance to canopy for a 1000watt DE HPS is ok? should it not be a distance like 3ft for this kind of lamp?
    i think good test to compare them, would be if you test them at the distance which you would use in a real grow.
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    MeGaKiLlErMaN Well-Known Member

    I ran it somewhere between 3-2 ft for a whole grow in a back uninsulated garage and with some crazy things (including power outages for a 3 days at different times) I managed .8g/ room W. I have no doubt I can move closer with good air flow and seeing these numbers. Moving further away will make the numbers slightly more consistent, but over all they will be smaller.

    The practicality test will be next in a 4x4 area.
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    PhotonFUD Well-Known Member

    Uniformity is far better with the CoBs than the other lights. Best spread closest to 400umoles and therefore should perform much better. I don't think there would be much disagreement that 800w of CoBs would outperform 1k HPS in almost any situation so that validates the importance of uniformity.

    I think your first COB reading of 270 looks to be off in comparison to the other corners, maybe something interfered with te reading?

    MeGaKiLlErMaN Well-Known Member

    Maybe but I took the top reading and bottom readings to get it. It's on the edge and I had no reflection on the left side and bottom for the cobs. For the HPS it was reflective on the left and top.

    Oh I know uniformity is what you want, but since I can have my plants at 1 ft or less then the second test will be fun. Of course that assumes that I have the LED error calculation.

    PhotonFUD Well-Known Member

    Maybe try a run with the CoBs at 1', then 2' and see if there is any significant difference. With the 400-550 spread you are getting now at 2' with 5x5 coverage, you could probably go up higher and even redeploy some CoBs as side lighting.

    You got the measuring tool to figure out the light hitting anywhere in your grow area so why not balance it all out.
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    Moldy Well-Known Member

    Subbed since I'm running an open DE hood at the moment. Looking to get into LED some day but I feel I'm too old to change and have no more money and don't understand LED's either. lol
    Wilderb likes this.

    SSGrower Well-Known Member

    Reflectors? To be "fair" to the led.

    SSGrower Well-Known Member

    Reflectors? To be "fair" to the led.

    MeGaKiLlErMaN Well-Known Member

    I could have been more fair but I don't use them so I don't think they are super needed. That's said I'll have them in a different setup next time.. And I should be around 1300PPFD in a 4x4 at my preferred height.

    SSGrower Well-Known Member

    This is where I think you may see a serious derailment in the experiment simply due to the directional differences between a "point source" the led and a linear source - the lamp. Comparing a johnathan apple to a braburn. Just my opinion backed by very little scientific data from questionable sources.

    BM9AGS Well-Known Member

    Awesome to have real world/non vendor data with HID. will you be doing a grow with these three lights? I understand you couldn't do clones with that much floor space but even seeds would give us some good info.
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    SSGrower Well-Known Member

    I meant are you using reflectors on the hps.

    Sorry I'm prertty much illiterate re read and assume you are using reflector on the DE lamp as well.
    Last edited: Sep 8, 2016

    MeGaKiLlErMaN Well-Known Member

    Yeah I am using on on it, but if I know a cob puts out a 120degree footprint I'm not too worried about the difference between 90-120.

    The only issue would be not having an adjustments.. But it is reading the par range properly. At least from what I'm seeing from what I was expecting on paper.

    MeGaKiLlErMaN Well-Known Member

    I have some cheapo seeds that I could run as well as the clones.. I will be putting up side by side results once I have the clones set and I might just run an extra in each.. Like 1GG#4, 2 Pinapple Express, and 1 Girl Scout cookies. In a 4x4.

    I appreciate the feedback, I hope that this is the end all for the whole talk and that it could be used as a marker for how to best grow with each light.

    SSGrower Well-Known Member

    Every time you use a different correction you are introducing a different weighting scheme for the sensor and would draw into question the validity of a coparison. What is the significance of this ? Dunno could be minimal could be big, most likely a function of the quality of any given meter and since we all seem to be cheap bastards I'd expect you will see greater variances than testing done with an actual spectral photometer. Don't let this discourage your efforts, I'm as interested as anyone in seeing what you find.

    MeGaKiLlErMaN Well-Known Member

    That's fair, keeping the current one still will prove a lot. I'll make graphs for the par outputs later so people have something to use.
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    SSGrower Well-Known Member

    We're all on the same squirrel hunt.
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    MeGaKiLlErMaN Well-Known Member

    So my mental math wasn't that great... and since its been too long to edit I cant edit the OP. However you can cross reference the numbers. After the auto calculation in excel took the average it was slightly different from what I did in my head.. so thats my bad.

    Attached are the excel file and Photo of the layout for use where ever you would like to use it.

    HPS vs COBS vs DE HPS.jpg

    Attached Files:

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    BM9AGS Well-Known Member

    Good update. I wondered how fair reflective surfaces would change the numbers.
    testiclees likes this.

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